1,111 research outputs found
Probing the extended non-Fermi liquid regimes of MnSi and Fe
Recent studies show that the non-Fermi liquid (NFL) behavior of MnSi and Fe
spans over an unexpectedly broad pressure range, between the critical pressure
p_c and around 2p_c. In order to determine the extension of their NFL regions,
we analyze the evolution of the resistivity rho(T) A(p)T^n at higher pressures.
We find that in MnSi the n=3/2 exponent holds below 4.8 GPa=3 p_c, but it
increases above that pressure. At 7.2 GPa we observe the low temperature Fermi
liquid exponent n=2 whereas for T>1.5 K, n=5/3. Our measurements in Fe show
that the NFL behavior rho T^{5/3} extends at least up to 30.5 GPa, above the
entire superconducting (SC) region. In the studied pressure range, the onset of
the SC transition reduces by a factor 10 down to T_c^onset(30.5 GPa)=0.23 K,
while the A-coefficient diminishes monotonically by around 50%.Comment: 2 pages, 2 figures, Proceedings SCES 200
Frustration-induced valence bond crystal and its melting in Mo3Sb7
121/123Sb nuclear quadrupole resonance and muon spin relaxation experiments
of Mo3Sb7 revealed symmetry breakdown to a nonmagnetic state below the
transition recently found at TS=50 K. The transition is characterized by a
distinct lattice dynamics suggested from narrowing of nuclear fields. We point
out that the Mo sublatice is a unique three-dimensional frustrated lattice
where nearest-neighbor and next-nearest-neighbor antiferromagnetic interactions
compete, and propose that tetragonal distortion to release the frustration
stabilizes long-range order of spin-singlet dimers, i.e., valence bond crystal,
which is thermally excited to the dynamic state with cubic symmetry.Comment: 4 pages. submitte
Magnetic Exciton Mediated Superconductivity in the Hidden-Order Phase of URu2Si2
We propose the magnetic exciton mediated superconductivity occurring in the
enigmatic hidden-order phase of URu2Si2. The characteristic of the massive
collective excitation observed only in the hidden-order phase is well
reproduced by the antiferro hexadecapole ordering model as the trace of the
dispersive crystalline-electric-field excitation. The disappearance of the
superconductivity in the high-pressure antiferro magnetic phase can naturally
be understood by the sudden suppression of the magnetic-exciton intensity. The
analysis of the momentum dependence of the magnetic-exciton mode leads to the
exotic chiral d-wave singlet pairing in the Eg symmetry. The Ising-like
magnetic-field response of the mode yields the strong anisotropy observed in
the upper critical field even for the rather isotropic 3-dimensional Fermi
surfaces of this compound.Comment: 5 pages, 4 figure
Evolution of Heterogeneous Antiferromagnetic State in URu2Si2: Study of Hydrostatic-Pressure, Uniaxial-Stress and Rh-Dope Effects
We have investigated the nature of the competition between hidden order and
antiferromagnetic (AF) order in URu_2Si_2 by performing the neutron scattering
experiments under hydrostatic-pressure P, uniaxial-stress sigma, and
Rh-substitution conditions. Hidden order observed at ambient pressure in pure
URu_2Si_2 is found to be replaced by the AF order by applying P, sigma along
the tetragonal basal plane, and by doping Rh. We discuss these experimental
results on the basis of the crystalline strain calculations, and suggest that
this phase transition is generated by the 0.1% increase of the tetragonal c/a
ratio. We have also found that the magnetic excitation observed in the hidden
order phase vanishes in the AF phase. We show that this variation can be
qualitatively explained by assuming the hidden order parameter to be
quadrupole.Comment: 4 pages, 4 figures, proceedings of workshop on Novel Pressure-Induced
Phenomena In Condensed Matter Systems, 2006 Fukuok
Replication Study of Candidate Genes Associated With Type 2 Diabetes Based On Genome-Wide Screening
OBJECTIVE—The present study was conducted to confirm possible associations between candidate genes from genome-wide association studies and type 2 diabetes in Japanese diabetic patients and a community-based general population. A total of 11 previously reported single-nucleotide polymorphisms (SNPs) from the TCF7L2, CDKAL1, HHEX, IGF2BP2, CDKN2A/B, SLC30A8, and KCNJ11 genes were analyzed
Precise study of the resonance at Q0=(1,0,0) in URu2Si2
New inelastic neutron scattering experiments have been performed on URu2Si2
with special focus on the response at Q0=(1,0,0), which is a clear signature of
the hidden order (HO) phase of the compound. With polarized inelastic neutron
experiments, it is clearly shown that below the HO temperature (T0 = 17.8 K) a
collective excitation (the magnetic resonance at E0 \approx 1.7 meV) as well as
a magnetic continuum co-exist. Careful measurements of the temperature
dependence of the resonance lead to the observation that its position shifts
abruptly in temperature with an activation law governed by the partial gap
opening and that its integrated intensity has a BCS-type temperature
dependence. Discussion with respect to recent theoretical development is made
SU(3)_flavor analysis of two-body weak decays of charmed baryons
We study two-body weak decays of charmed baryons \Lambda_c and \Xi_c into an
octet or decuplet baryon and a pseudoscalar meson employing the SU(3) flavor
symmetry. Using certain measured Cabibbo-favored modes, we fix the reduced
amplitudes and predict the branching ratios of various decays of charmed
baryons in the Cabibbo-enhanced, -suppressed and -doubly suppressed modes.Comment: 25 pages, No figure, Phys. Rev. D (to appear
The amphioxus genome and the evolution of the chordate karyotype
Lancelets ('amphioxus') are the modern survivors of an ancient chordate lineage, with a fossil record dating back to the Cambrian period. Here we describe the structure and gene content of the highly polymorphic approx520-megabase genome of the Florida lancelet Branchiostoma floridae, and analyse it in the context of chordate evolution. Whole-genome comparisons illuminate the murky relationships among the three chordate groups (tunicates, lancelets and vertebrates), and allow not only reconstruction of the gene complement of the last common chordate ancestor but also partial reconstruction of its genomic organization, as well as a description of two genome-wide duplications and subsequent reorganizations in the vertebrate lineage. These genome-scale events shaped the vertebrate genome and provided additional genetic variation for exploitation during vertebrate evolution
Search for Charmless Two-body Baryonic Decays of B Mesons
We report the results of a search for the rare baryonic decays , , and . The analysis
is based on a data set of events collected by the
Belle detector at the KEKB collider. No statistically significant
signals are found, and we set branching fraction upper limits , , and at the 90% confidence level.Comment: 6 pages, 4 figures and 1 table. Submitted to Phys. Rev. D Rapid
Communication
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